• Journal of ILASS-Korea
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• v.27 no.1
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• pp.42-49
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• 2022

Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.172-175
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• 2020

최근 스마트시티, 자율 주행 자동차 등 기계에 의해 소비되는 영상 데이터의 양이 증가함에 따라 기계의 임무 수행 능력을 향상시킬 수 있는 압축기술이 필요하게 되었다. 그런데, 전통적 방식의 영상 코덱은 사람의 인지 화질 특성을 고려해 개발된 기술이기 때문에 기계의 임무 수행에 필수적인 정보 외에도 불필요한 정보가 존재한다. 따라서 사람이 아닌 기계의 임무 수행에 대해 효율적으로 영상을 압축하기 위한 비디오 코덱 기술이 필요하다. 이와 관련하여, 최근 MPEG에서 Video Coding for Machines라는 영상 압축기술에 대한 표준화가 논의되고 있다. 본 논문에서는 기계를 위한 영상 압축기술의 연구배경과 연구를 통해 전통적인 영상 압축 코덱 방식과 neural network 기반 압축 코덱 방식에 대해 각각의 방식이 머신비전 임무를 수행한 정확도를 기준으로 영상 압축성능을 비교해 효율적인 압축 코덱 방식에 대해 분석한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.325-327
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• 2021

본 연구에서는 대학생의 자아존중감, 전공만족도, 외모만족도, 취업스트레스의 관계를 확인하고, 이에 대한 제언을 제시하고자 한다. 본 연구는 B광역시에 소재한 재학생을 대상으로 실시하며, 그에 따른 연구결과에 대한 프로그램을 개발하고, 다양한 영향요인을 탐색하고자 한다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.92-99
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• 1997

A model reference adaptive control(MRAC) theory is very useful for controlling a plant of which the parameters are unknown or vary during operation usint only input-output signal of plant. In this study, 2' nd order discreter time MRAC controller is designed for an electrohydraulic position control system which is represented with nonlinear mathematical model and the least square method is adopted for the para-meter adjustment law. This control algorthm is applied to the position control of electrohydraulic servosystem through computer simulation and the effect of the change of load, sampling time upon the performance following reference model and upon the performance of estimating plant parameters are examined.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.671-672
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• 2022

본 연구에서는 대학생의 자기결정성, 가족탄력성, 사회적지지, 대학생활적응의관계를 확인하고, 이에 대한 제언을 제시하고자 한다. 본 연구는 B광역시에 소재한 재학생을 대상으로 실시하며, 그에 따른 연구결과에 대한 프로그램을 개발하고, 다양한 영향요인을 탐색하고자 한다.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1127-1134
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• 2023

In this paper, we proposes a study on air gap control for magnetic levitation of transverse flux permanent magnet electromagnets. In general, mechanical systems have a high failure rate of bearings. Bearings in particular are problematic because they have high surface wear rate and degradations. To solve this problem, replacing the bearing with a magnetic levitation electromagnet system can provide lightweight and efficiency improvements. However, precise air gap control is essential to control the magnetic levitation electromagnet system. Therefore, in this paper, we identify the instable cause of gap control through a mathematical modeling and verify through experiment a control algorithm that can use compensation.

• Journal of agriculture & life science
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• v.50 no.4
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• pp.169-177
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• 2016

This study was carried out to compare microbiological and hygienic quality characteristics of the products reached expiration date among meat products distributing in markets. A total of 20 meat products(6 hams, 3 bacons and 11 sausages) were examined for analyses of pH, Aw, TBARS, VBN, total aerobic microbial counts, and meat colors. The pH values of samples were between 5.33 and 6.59. The water activity (Aw) of samples ranged 0.90-0.93. TBARS and VBN values of samples were 0.11-0.59 and 2.37~14.75, respectively. The contaminated levels of total aerobic bacteria were less than 2.80 CFU/g. In meat color, L*, a*, and b* values of samples were in the range of 56-72, 5.2-34 and 0.7-16, respectively. It is suggested that the quality difference of meat products is attributed to the different additives and manufacturing processes. Therefore, we suggest that the results of this study are not only applied for evaluation of the microbiological and hygienic safety but also served as fundamental information for re-establishing the shelf-life of meat products.

• 레미콘
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• no.9 s.9
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• pp.102-104
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• 1986

• 대한한약
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• s.2
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• pp.422-423
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• 1998

• Korean Security Journal
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• no.51
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• pp.293-313
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• 2017

The purpose of this study is to analyze the changes of regional clusters of national 16 areas on the assembly & demonstration in 2010 and 2015. The results of this study were as follows by using hierarchical cluster analysis. First, the regional clusters on the assembly & demonstration in 2010 were divided into three clusters in the first step: (1) Gwangju, Chungnam, Incheon, Chungbuk, Gyeongbuk, Daegu, Gangwon, Jeju, Daejeon, (2) Jeonnam, Gyeongnam, Busan, Jeonbuk, Ulsan, Gyeonggi, (3) Seoul. Second, the regional clusters on the assembly & demonstration in 2015 were divided into three clusters in the first step: (1) Ulsan, Gangwon, Chungbuk, Chungnam, Incheon, Gyeongbuk, Jeonnam, Gwangju, Jeju, Daegu, Daejeon, (2) Busan, Jeonbuk, Gyeongnam, (3) Seoul, Gyunggi. Third, The regional clusters on the assembly & demonstration were Busan, Jeonbuk, Gyeongnam of 'assembly & demonstration management area(labor related)', and Seoul, Gyeonggi of 'assembly & demonstration frequency areas' in 2015. This suggests that policing policies related to assembly & demonstration can be established and implemented flexibly in consideration of the degree of increase and decrease in assembly & demonstration by districts. Furthermore, it will be helpful to manage assembly & demonstration based on the 'police for human rights'.